The present invention relates generally to hollow doors and more specifically to a core structure inserted within a hollow door to provide support for the skins of the door.
Hollow core doors are commonly used in many types of buildings. The common structure of a hollow core door includes a pair of door skins which are separated by a wood frame. The wood frame has vertical wood stiles joined to upper and lower horizontal wood rails. The wood stiles and rails form the edges of the door. A lock block may also be included in the area of the door where locks and handles are attached. The lock block provides the additional support that is needed to secure a lock in the door. A hollow area is enclosed between the two door skins and within the frame. The hollow area typically requires some type of structural reinforcement.
One type of reinforcement commonly used in hollow core doors is a honeycomb core structure that is glued in place between the door skins. The honeycomb core structure may be, for example, corrugated board. The honeycomb structure is supplied in an unexpanded manner. The honeycomb core is stretched across the skin of the interior of the door. One problem with using such a honeycomb core structure is that it is difficult to stretch to achieve an even honeycomb pattern within the door. Commonly, the honeycomb core must be overstretched and then manipulated into place. This process is labor intensive and thus not a cost effective manner for manufacturing the door.
The honeycomb core fully extends between the horizontal rails and vertical stiles to completely fill the hollow interior. Consequently, more core material is inserted within the interior of the door than is actually required for support. The extra core material increases the cost of the door.
Another type of door reinforcement includes solid blocks placed strategically between the door skins. The solid blocks are commonly formed of laminated strips of corrugated or from pieces of styrofoam. One disadvantage of solid block is that they use a large quantity of material making them more expensive. Also, these solid blocks require a significant amount of glue to be spread over their entire surface to bond to the outer skins of the door.
The outer skins of hollow core doors maybe formed using a planar flush panel or they may have a contoured colonial-type molded panel configuration. In a colonial-type panel configuration, a portion of the panel extends within the hollow interior of the door. The thickness of the hollow space in that area is reduced. Inserting a honeycomb structure or core in such a door is undesirable since the honeycomb core would have to be reduced in thickness in the areas where the panel extends within the hollow interior of the door. Although this has been done, because the honeycomb does not stretch evenly, the areas reduced in thickness do not always align where desired.
It is therefore desirable to provide a corrugated structural paper core filler or support for a hollow core door which is cost effective by being easy to manufacture and by using a reduced amount of material.